Biofloc technology has been applied successfully in the intensive aquaculture of several fish and shrimp species. The growth of heterotrophic microorganisms can be stimulated through adding extra carbon, which reduces...Biofloc technology has been applied successfully in the intensive aquaculture of several fish and shrimp species. The growth of heterotrophic microorganisms can be stimulated through adding extra carbon, which reduces the nitrogen level in the water and provides microbial protein to the animals. However, most of the studies and practical applications have been conducted in freshwater and marine environment. This paper focused on brine shrimp Artemia that lives in high salinity environment together with other halophilic or halotolerant microorganisms. The effect of carbon supplementation on Artemia growth, water quality, and microbial diversity of biofl ocs was studied in the closed culture condition without any water exchange. The salinity of the culture medium was 100. A 24-d culture trial was conducted through supplementing sucrose at carbon/nitrogen (C/N) ratio of 5, 15, and 30 (Su5, Su15, and Su30), respectively. The culture without adding sucrose was used as a control. Artemia was fed formulated feed at a feeding ration of 60% recommended feeding level. The results showed that sucrose supplementation at higher C/N ratio (15 and 30) signifi cantly improved the Artemia survival, growth and water quality ( P <0.05). Addition of sucrose at C/N ratio of 15 and 30 significantly increased biofloc volume (BFV)( P <0.05). The Illumina MiSeq sequencing analysis showed that supplementing carbon at C/N ratio of 15 had a better total bacterial diversity and richness, and shaped the microbial composition at genera level. This study should provide information for studying the mechanism of biofloc technology and its application in high salinity culture conditions.展开更多
Elemental analyzer/isotope ratio mass spectrometry(EA/TRMS) has been widely applied to analyze the^(15)N/^(14)N isotope composition(δ^(15)N) of plants and soils,but the δ^(15)N results may be inaccurate due to incom...Elemental analyzer/isotope ratio mass spectrometry(EA/TRMS) has been widely applied to analyze the^(15)N/^(14)N isotope composition(δ^(15)N) of plants and soils,but the δ^(15)N results may be inaccurate due to incomplete combustion of the high-C/N-ratio plant samples by EA.Therefore,it is necessary to develop a method to solve the problem of imperfect combustion.In this study,we used two methods:1) adding copper oxide powder to the samples,and 2) increasing the O_2 flow(from 100 mL min^(-1) to 200 mL min^(-1)) for the auto sampler inlet purge line of the EA.The δ^(15)N values of the plant samples became more positive and tended to be stable after complete combustion.Also,the required blank samples for each plant sample decreased with increasing amount of the added CuO powder.However,at 200 mL min^(-1) of the oxygen flow in the EA,complete combustion could not be achieved without adding copper oxide,but this was done with decreased amount of CuO powder.Therefore,mixing cupric oxide into the high-C/N-ratio samples was an efficient,simple and convenient way to solve the problem of imperfect combustion in the EA.展开更多
Objective:To explore the application value of neutrophil/lymphocyte ratio (NLR) combined with high sensitive C reactive protein (hs-CRP) in the evaluation of community acquired pneumonia (CAP). Methods:From November 2...Objective:To explore the application value of neutrophil/lymphocyte ratio (NLR) combined with high sensitive C reactive protein (hs-CRP) in the evaluation of community acquired pneumonia (CAP). Methods:From November 2015 to October 2016, 58 cases of CAP patients admitted in our department were selected as research objects and were divided into low risk group and high risk group according to the PSI score and CURB-65 standard for evaluation. They were divided into improved group (48 cases) and death group (10 cases) according to prognosis. Hs-CRP was determined by immunoturbidimetric assay, procalcitonin (PCT) by immunofluorescence, NLR by count method of laser scattering, and white blood (WBC) was counted. The differences in WBC, PCT, NLR and hs-CRP between different risk groups were compared, and the correlation was evaluated using Spearman's rank correlation analysis method. The changes in indexes were observed in the improved and death cases. Results:The high risk group had higher NLR, PCT and hs-CRP than low risk group (P<0.05), while no significant difference was found in WBC (P>0.05). No correlation was found between NLR and WBC, while a strong correlation was found between hs-CRP and PCT. The WBC, PCT, NLR and hs-CRP levels were significantly lower in the improved group than the death group (P<0.05). Conclusions:NLR combined with hs-CRP, WBC, and PCT has a good assessment of the severity of CAR, and high levels of NLR, hs-CRP, WBC, and PCT predict the severity of the disease and poor prognosis.展开更多
The aims of the present work are to evaluate the overaging behaviour of the investigated Cu-enriched alloy and to assess its mechanical behaviour,in terms of the tensile and fatigue strength,at room temperature and at...The aims of the present work are to evaluate the overaging behaviour of the investigated Cu-enriched alloy and to assess its mechanical behaviour,in terms of the tensile and fatigue strength,at room temperature and at 200℃,and to correlate the mechanical performance with its microstructure,in particular with the secondary dendrite arm spacing(SDAS).The mechanical tests carried out on the overaged alloy at 200℃ indicate that the addition of about 1.3 wt.%Cu to the A357 alloy enables to maintain ultimate tensile strength and yield strength values close to 210 and 200 MPa,respectively,and fatigue strength at about 100 MPa.Compared to the quaternary(Al−Si−Cu−Mg)alloy C355,the A357−Cu alloy has greater mechanical properties at room temperature and comparable mechanical behaviour in the overaged condition at 200℃.The microstructural analyses highlight that SDAS affects the mechanical behaviour of the peak-aged A357−Cu alloy at room temperature,while its influence is negligible on the tensile and fatigue properties of the overaged alloy at 200℃.展开更多
The investigation on lath martensitic transfor- mation has been carried out for 24SiMnNi2CrMoA steel using transmission electron microscopy (TEM) and X-ray diffraction.The austenite and martensite in the alloy adopt t...The investigation on lath martensitic transfor- mation has been carried out for 24SiMnNi2CrMoA steel using transmission electron microscopy (TEM) and X-ray diffraction.The austenite and martensite in the alloy adopt the intermediate orientation relationship between Kurdjumov-Sachs and Nishiyama.The adjacent laths in a packet are small-angle related or twin-related.The retained austenites which accommodate shape deformation of martensites appear commonly between adjacent laths.High Si content increases the volume fraction of retained austenites and its stability.The excellent combination of high strength and toughness of this steel is attributed to its fine martensite laths mingled with more than 5% continuous retained austenite films.展开更多
Improving the thermal stability of diamond and other superhard materials has great significance in various applications. Here, we report the synthesis and characterization of bulk diamond–cBN–B4C–Si composites sint...Improving the thermal stability of diamond and other superhard materials has great significance in various applications. Here, we report the synthesis and characterization of bulk diamond–cBN–B4C–Si composites sintered at high pressure and high temperature（HPHT, 5.2 GPa, 1620–1680 K for 3–5 min）. The results show that the diamond, cBN, B4C,BxSiC, SiO2 and amorphous carbon or a little surplus Si are present in the sintered samples. The onset oxidation temperature of 1673 K in the as-synthesized sample is much higher than that of diamond, cBN, and B4C. The high thermal stability is ascribed to the covalent bonds of B–C, C–N, and the solid-solution of BxSiC formed during the sintering process. The results obtained in this work may be useful in preparing superhard materials with high thermal stability.展开更多
基金Supported by the Yangtze Scholars and Innovative Research Team in University of Ministry of Education of China(No.IRT_17R81)the Technology Support Project of Tianjin(No.16YFZCNC00810)
文摘Biofloc technology has been applied successfully in the intensive aquaculture of several fish and shrimp species. The growth of heterotrophic microorganisms can be stimulated through adding extra carbon, which reduces the nitrogen level in the water and provides microbial protein to the animals. However, most of the studies and practical applications have been conducted in freshwater and marine environment. This paper focused on brine shrimp Artemia that lives in high salinity environment together with other halophilic or halotolerant microorganisms. The effect of carbon supplementation on Artemia growth, water quality, and microbial diversity of biofl ocs was studied in the closed culture condition without any water exchange. The salinity of the culture medium was 100. A 24-d culture trial was conducted through supplementing sucrose at carbon/nitrogen (C/N) ratio of 5, 15, and 30 (Su5, Su15, and Su30), respectively. The culture without adding sucrose was used as a control. Artemia was fed formulated feed at a feeding ration of 60% recommended feeding level. The results showed that sucrose supplementation at higher C/N ratio (15 and 30) signifi cantly improved the Artemia survival, growth and water quality ( P <0.05). Addition of sucrose at C/N ratio of 15 and 30 significantly increased biofloc volume (BFV)( P <0.05). The Illumina MiSeq sequencing analysis showed that supplementing carbon at C/N ratio of 15 had a better total bacterial diversity and richness, and shaped the microbial composition at genera level. This study should provide information for studying the mechanism of biofloc technology and its application in high salinity culture conditions.
文摘Elemental analyzer/isotope ratio mass spectrometry(EA/TRMS) has been widely applied to analyze the^(15)N/^(14)N isotope composition(δ^(15)N) of plants and soils,but the δ^(15)N results may be inaccurate due to incomplete combustion of the high-C/N-ratio plant samples by EA.Therefore,it is necessary to develop a method to solve the problem of imperfect combustion.In this study,we used two methods:1) adding copper oxide powder to the samples,and 2) increasing the O_2 flow(from 100 mL min^(-1) to 200 mL min^(-1)) for the auto sampler inlet purge line of the EA.The δ^(15)N values of the plant samples became more positive and tended to be stable after complete combustion.Also,the required blank samples for each plant sample decreased with increasing amount of the added CuO powder.However,at 200 mL min^(-1) of the oxygen flow in the EA,complete combustion could not be achieved without adding copper oxide,but this was done with decreased amount of CuO powder.Therefore,mixing cupric oxide into the high-C/N-ratio samples was an efficient,simple and convenient way to solve the problem of imperfect combustion in the EA.
文摘Objective:To explore the application value of neutrophil/lymphocyte ratio (NLR) combined with high sensitive C reactive protein (hs-CRP) in the evaluation of community acquired pneumonia (CAP). Methods:From November 2015 to October 2016, 58 cases of CAP patients admitted in our department were selected as research objects and were divided into low risk group and high risk group according to the PSI score and CURB-65 standard for evaluation. They were divided into improved group (48 cases) and death group (10 cases) according to prognosis. Hs-CRP was determined by immunoturbidimetric assay, procalcitonin (PCT) by immunofluorescence, NLR by count method of laser scattering, and white blood (WBC) was counted. The differences in WBC, PCT, NLR and hs-CRP between different risk groups were compared, and the correlation was evaluated using Spearman's rank correlation analysis method. The changes in indexes were observed in the improved and death cases. Results:The high risk group had higher NLR, PCT and hs-CRP than low risk group (P<0.05), while no significant difference was found in WBC (P>0.05). No correlation was found between NLR and WBC, while a strong correlation was found between hs-CRP and PCT. The WBC, PCT, NLR and hs-CRP levels were significantly lower in the improved group than the death group (P<0.05). Conclusions:NLR combined with hs-CRP, WBC, and PCT has a good assessment of the severity of CAR, and high levels of NLR, hs-CRP, WBC, and PCT predict the severity of the disease and poor prognosis.
文摘The aims of the present work are to evaluate the overaging behaviour of the investigated Cu-enriched alloy and to assess its mechanical behaviour,in terms of the tensile and fatigue strength,at room temperature and at 200℃,and to correlate the mechanical performance with its microstructure,in particular with the secondary dendrite arm spacing(SDAS).The mechanical tests carried out on the overaged alloy at 200℃ indicate that the addition of about 1.3 wt.%Cu to the A357 alloy enables to maintain ultimate tensile strength and yield strength values close to 210 and 200 MPa,respectively,and fatigue strength at about 100 MPa.Compared to the quaternary(Al−Si−Cu−Mg)alloy C355,the A357−Cu alloy has greater mechanical properties at room temperature and comparable mechanical behaviour in the overaged condition at 200℃.The microstructural analyses highlight that SDAS affects the mechanical behaviour of the peak-aged A357−Cu alloy at room temperature,while its influence is negligible on the tensile and fatigue properties of the overaged alloy at 200℃.
文摘The investigation on lath martensitic transfor- mation has been carried out for 24SiMnNi2CrMoA steel using transmission electron microscopy (TEM) and X-ray diffraction.The austenite and martensite in the alloy adopt the intermediate orientation relationship between Kurdjumov-Sachs and Nishiyama.The adjacent laths in a packet are small-angle related or twin-related.The retained austenites which accommodate shape deformation of martensites appear commonly between adjacent laths.High Si content increases the volume fraction of retained austenites and its stability.The excellent combination of high strength and toughness of this steel is attributed to its fine martensite laths mingled with more than 5% continuous retained austenite films.
基金supported by the National Natural Science Foundation of China(Grant No.51301075)the Project of Development and Reform Commission of Jilin Province,China(Grant No.2014Y136)
文摘Improving the thermal stability of diamond and other superhard materials has great significance in various applications. Here, we report the synthesis and characterization of bulk diamond–cBN–B4C–Si composites sintered at high pressure and high temperature（HPHT, 5.2 GPa, 1620–1680 K for 3–5 min）. The results show that the diamond, cBN, B4C,BxSiC, SiO2 and amorphous carbon or a little surplus Si are present in the sintered samples. The onset oxidation temperature of 1673 K in the as-synthesized sample is much higher than that of diamond, cBN, and B4C. The high thermal stability is ascribed to the covalent bonds of B–C, C–N, and the solid-solution of BxSiC formed during the sintering process. The results obtained in this work may be useful in preparing superhard materials with high thermal stability.
